Treatment of hydrocarbons



Patented Jan. 14,

UNITED STATES v 2,027,394 TREATMENT OF HYDBOCABBONS Edward W. McMullan,Philadelphia, Pa., assignor, by mesne assignments, to GasolineAntioxidant Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application December 10, 1930, Serial No. 501,479

Claims.

The present invention relates to the art of stabilizing hydrocarbonoils, and has particular reference to the treatment of low boilinghydrocarbon oils such as naphtha, gasoline, and kero- 5 sene to renderthe same more stable, and also to the product resulting from suchtreatment.

Such low boiling oils even after being refined, may undergo spontaneouschemical changes upon standing which cause the formation ofobjectionable gum which may precipitate, causing a deposit to form, orwhich may remain in solution or suspension therein as a cloud or hazeuntil the oil is vaporized, whereupon it may deposit, as for exampleupon motor parts or wicks.

The phenomenon of gum formation is particularly noticeable in the caseof oils which result from cracking higher boiling oils. As mostcommercial gasolines contain distillates which result from cracking, andsince in recent practice there 20 is a trend toward increasing thecontent of cracked distillates in gasoline, the problem of gum formationis of prime importance.

My invention is based upon the discovery that the aforesaidobjectionable formation of gum in hydrocarbon oils, particularly lowboiling hydrocarbon oils such as naphtha, gasoline, and kerosene, uponallowing such oils to stand for some time, and particularly when exposedto direct or diifused light, more particularly sunlight, may bematerially inhibited by dissolving in the oil a small amount of certaincompounds having an azo, hydrazo, or azoxy group. These compounds arecharacterized in that they contain two hydrocarbon radicals joined toone another through a nitrogen to nitrogen linkage. This will be seenfrom the following formulae in which R and R represent the hydrocarbonradicals which may be alkyl or aryl or substitute alkyl or aryl groups:

A20 compounds Hydrazo compounds R-N-N-R' Azoxy compounds RNNR'advantage. 0! the substances named I prefer to use azo benzene and/orhydrazo benzene.

The amount of these substances necessary to be added to the hydrocarbonoil in order to inhibit gum formation when the oil is allowed to 5 standdepends upon such factors as the particular oil being stabilized and theconditions to which the oil is to be exposed. These factors may be takeninto consideration in determining the proper amount of gum inhibitor tobe added to any 10 particular oil. In general, the amount of guminhibitor required does not exceed 1% by weight of the oil, and in mostcases the addition to the oil of an amount of the order 01 0.05% to 0.5%by weight is ample to inhibit substantial gum 15 formation.

In accordance withimy invention, a small quantity of one or a mixture oftwo or more of the compounds named is added to the oil, it beingpreferred to agitate the oil to facilitate solution 20 of the guminhibitor therein. Although this addition may be made prior tocompletion of the ordinary refining processes, it is preferred to addthe gum inhibitor subsequent to refining operations.

My process will be more completely understood by reference to thefollowing examples:

Example 1 To a blended gasoline consisting of a 50--50 39 mixture ofstraight run gasoline with gasoline obtained by cracking the gas oilfraction of a West Texas crude oil, which by the copper dish test gave21 mg. of gum, there was added 0.1% by weight of azo benzene. Afterstanding 51 35 hours in direct sunlight the sample containing azobenzene had a gum value of only 28 mg. per cc. A portion of the samegasoline without azo benzene when allowed to stand for a similar periodof time and under like conditions, showed 4 a gum value of 129 mg. per100 cc. After 151 hours exposure under the above conditions thestabilized portion showed a gum value of 46 mg. per 100 cc., while theportion to which azo benzene had not been added showed 224 mg. of gumper 45 100 cc.

Example 2 A blended gasoline in the proportions of approximately 50parts of straight run gasoline to 50 50 parts of cracked gasoline wasstabilized by adding thereto .05% by weight of hydrazo benzene. Samplesof this stabilized gasoline and of the same gasoline without theaddition of hydrazo benzene were permitted to stand for 45 hours. 55

There was only a trace of gum by the copper dish test in each of thesamples at the beginning 01' the test period. At the end of 45 hours thesample to which hydrazo benzene had not been added showed a gum value of50 mg. per 100 00., while the sample to which hydrazo benzene had beenadded showed only 6 mg. 01' gum per 100 cc. After a period of 140 hoursof standing under the same conditions the former had a gum value 01' 119mg. per 100 cc., while the latter showed only 37 mg. of gum per 100 cc.

Example 3 To a blended gasoline containing approximately 50 parts ofstraight run gasoline and 50 parts oi' cracked gasoline there was added0.1% by weight of azoxy benzene. A sample of the gasoline so treatedalong with a sample of the gasoline which was not treated were permittedto stand for 76 hours exposed to light. The untreated sample after suchperiod of time showed a gum value of 119 mg. per 100 00., while that ofthe untreated sample showed a gum value of only 73 mg. per 100 cc.

From these examples it will be seen that although my process does notentirely prevent gum formation in hydrocarbon oils, it is operable tosubstantially inhibit gum formation and to make the oils more resistantto the formation of gum.

Herein and in the appended claims, when the term "gums is used, it is tobe understood to include those solid and/or semi-solid compounds whichwhen not inhibited form due to spontaneous chemical reaction when thelow boiling hydrocarbon oils containing gum forming compounds areexposed to storage conditions. Also, in the appended claims, when theamount of substance added to the oil to inhibit gum formation is definedas a small amount, it is to be understood that such term describesamounts which are readily soluble in the oil. Such amounts, in general,will be of the order of 1% or less by weight of the oil.

Also where in the appended claims low boiling hydrocarbon oil, which hasbeen illustrated herein by naphtha, gasoline, and kerosene, is referredto, such term will be understood to contemplate hydrocarbons having aviscosity of the order 01, or, more particularly less than 45 secondsSaybolt Universal at 100 F., and having 5 a 50% boiling point asdetermined by A. S. T. M. Method D 86-30, below 550 F., those having a50% boiling point of the order of 350 F'., or lower, being morespecifically contemplated.

What I claim is:

1. A motor fuel comprising cracked gasoline normally tending todeteriorate upon storage by gum formation, and stabilized against suchgum formation by having incorporated therein a small amount of asubstance selected from the group consisting of azo benzene, azoxybenzene and hydrazo benzene, said amount being suiilcient substantiallyto retard said gum formation.

2. A motor fuel comprising cracked gasoline, normally tending todeteriorate upon storage by gum formation and discoloration, stabilizedagainst such deterioration by the addition thereto of a small amount ofazoxy benzene, said amount being sufficient substantially to retard suchdeterioration.

3. A motor fuel comprising cracked gasoline, normally tending todeteriorate upon storage by gum formation and discoloration, stabilizedagainst such deterioration by the addition thereto of a. small amount ofhydrazo benzene, said amount being sufficient substantially to retardsuch deterioration.

4. A cracked gasoline comprising constituents of the type which areunstable upon storage and 'tend to form gum particularly when exposed tothe direct light rays of the sun and containing azobenzene as astabilizer thereof in quantity less than .1 percent by weight.

5. A cracked gasoline, normally tending to de teriorate upon storage bygum formation and 40 discoloration, stabilized against suchdeterioration by the addition thereto of a small amount of azo benzene,said amount being sufficient substantially to retard such deterioration.

EDWARD W. McMULLAN.

